A numerical identifier included in supported blockchain signatures to distinguish the network on which an authorization is intended to work.

When a node switches to a heavier or longer fork and drops recently accepted blocks.

The UTXO sent back to yourself when you spend more than the payment amount.

A fee-bumping trick that spends an unconfirmed output with a high-fee child so miners take both.

The first transaction in a Bitcoin block, which pays the block reward. Not related to the company Coinbase.

A wallet whose keys stay offline, often on a hardware device or paper backup, used for longer-term storage.

In common Bitcoin usage, inclusion in a block gives one confirmation, and each subsequent block on the accepted chain adds another.

Math that protects confidentiality, integrity, and authenticity. Blockchains rely on hashes and signatures.

Who holds the keys. A custodian can move funds on a client's behalf and takes operational and legal responsibility.